^Hugo, Adam Bedau. Punishment, Crime and the State. Stanford Encyclopedia of Philosophy. February 19, 2010 [2010-08-04]. "The search for a precise definition of punishment that exercised some philosophers (for discussion and references see Scheid 1980) is likely to prove futile: but we can say that legal punishment involves the imposition of something that is intended to be burdensome or painful, on a supposed offender for a supposed crime, by a person or body who claims the authority to do so."

^McAnany, Patrick D. Punishment. Online. Grolier Multimedia Encyclopedia. August 2010 [2010-08-04]. "Punishment describes the imposition by some authority of a deprivation — usually painful — on a person who has violated a law, rule, or other norm. When the violation is of the criminal law of society there is a formal process of accusation and proof followed by imposition of a sentence by a designated official, usually a judge. Informally, any organized group — most typically the family, in rearing children — may punish perceived wrongdoers."

^Hugo, Adam Bedau. Theory of Punishment. Stanford Encyclopedia of Philosophy. February 19, 2010 [2010-08-04]. "Punishment under law... is the authorized imposition of deprivations — of freedom or privacy or other goods to which the person otherwise has a right, or the imposition of special burdens — because the person has been found guilty of some criminal violation, typically (though not invariably) involving harm to the innocent. (The classical formulation, conspicuous in Hobbes, for example, defines punishment by reference to imposing pain rather than to deprivations.) This definition, although imperfect because of its brevity, does allow us to bring out several essential points."

^Peters, Richard Stanley. Ethics and Education. 1966: 267–268. JSTOR3120772. "Punishment... involves the intentional infliction of pain or of something unpleasant on someone who has committed a breach of rules... by someone who is in authority, who has a right to act in this way. Otherwise, it would be impossible to distinguish 'punishment' from 'revenge'. People in authority can, of course, inflict pain on people at whim. But this would be called 'spite' unless it were inflicted as a consequence of a breach of rules on the part of the sufferer. Similarly a person in authority might give a person £5 as a consequence of his breaking a rule. But unless this were regarded as painful or at least unpleasant for the recipient it could not be counted as a case of 'punishment'. In other words at least three criteria of (i) intentional infliction of pain (ii) by someone in authority (iii) on a person as a consequence of a breach of rules on his part, must be satisfied if we are to call something a case of 'punishment'. There are, as is usual in such cases, examples that can be produced which do not satisfy all criteria. For instance there is a colloquialism which is used about boxers taking a lot of punishment from their opponents, in which only the first condition is present. But this is a metaphorical use which is peripheral to the central use of the term.

In so far as the different 'theories' of punishment are answers to questions about the meaning of 'punishment', only the retributive theory is a possible one. There is no conceptual connection between 'punishment' and notions like those of 'deterrence', 'prevention' and 'reform'. For people can be punished without being prevented from repeating the offence, and without being made any better. It is also a further question whether they themselves or anyone else is deterred from committing the offence by punishment. But 'punishment' must involve 'retribution', for 'retribution' implies doing something to someone in return for what he has done.... Punishment, therefore, must be retributive—by definition."

^Kleining, John. R.S. Peters on Punishment. British Journal of Educational Studies. October 1972, 20 (3): 259–269. doi:10.1080/00071005.1972.9973352. JSTOR3120772. "Unpleasantness inflicted without authority is revenge, and if whimsical, is spite.... There is no conceptual connection between punishment, or deterrence, or reform, for people can be punished without being prevented from repeating the offence, and without being made better. And it is also a further question whether they themselves, or anyone else is deterred from committing the offence by punishment."